Extension arm



FIG. 1 is a perspective view of the extension arm; FIG. 2 is a right side view of the extension arm of FIG. 1; FIG. 3 is a front view of the extension arm of FIG. 1; FIG. 4 is a left side view of the extension arm off FIG. 1; FIG. 5 is a top view of the extension arm of FIG. 1; FIG. 6 is a bottom view of the extension arm of FIG. 1; and, FIG. 7 is a rear view of the extension arm of FIG. 1. 

The ornamental design for an extension arm, as shown and described. 